By deleting the groups using a query like this:
DELETE FROM table_name WHERE id = 'x';
where x is a number, MySQL won't reset the start number, however:
DELETE FROM table_name; or
TRUNCATE TABLE table_name;
should remove all the records and reset the next auto number data.
If you have altered the id to a smallint then you should have no problems in the forseeable future.
I've designed the DB for YSE 2 and I've ensured that this sort of thing won't happen (unless you're running a service like
www.hardforum.com - in which case you'd be doing some hefty optimisation anyway!).